Method of making insulator caps



May 26, 1931. D w 1,806,726

METHOD OF MAKING INSULA'I'OR CAPS Filed Sept. 26, 1928 IIIIIIIII'II Q 'FLOYD 0. WENN INVENTOR.

Byfw

ATTORNEY Patented May 26, 1931 UNITED STATES PATENT OFFICE FLOYD n. wnnn, or BINGHAMTON. new YORK, Assmnon TO THE BREWER- TITCHENER CORPORATION, OF CORTLAND,

YORK

NEW YORK, A. CORPORATION OF NEW METHOD OF MAKING INSULATOR CAPS Application filed September 26, 1928. Serial No. 308,375. I

This invention generically relates to the art of hollow metal swaging, and more particularly pertains to an improved process for stamping up a shell-like socketed cap member affording a radially undercut mouth rim adapted to securely mount therein, an in sulator disc of the suspension type as used in connection with high-tension electric transmission lines switch stands or the like. The primary object of my method. is to effectively shape up in a cold state, a sheetmetal blank into an undercut chambered product of the character indicated, in which the wall thickness may be properly maintained when the dome thereof is extruded to provide for a partitioned link chamber adapted to pivotally mount the cap attachment means therein.

Such protective cap is required to possess the utmost of reliability as to structural material for the reason that it is both difficult.

and expensive to replace any defective insulator cap assembly, once it has been placed in service. The present invention seeks to reduce factory costs and topromote a more uniform and reliable quality of such products as compared with the conventional cast type of insulator cap.

To this end and the accomplishment of other. new and useful results, my invention further consists in novel features of structure and manipulation, all of which will hereinafter be more fully described.

Reference is had to the accompanying one sheetof drawings which are illustrative of a specific embodiment of my invention, in which like characters of reference indicate like parts, and in which: V

Fig. 1 represents a fragmental portio of a series of alternate insulator discs arranged in tandem, each such unit being .interconnected by means of my interposed cap devices and the assembly primarily intended to suspend a high tension transmission line.

Fig. 2 cross-sectionally represents the manner in which a sheet-metal blank is first to bedrawn up into a cup-shaped structure having a flaring skirt portion whose rim terminates in a relatively small open mouth dimension; 7

completed cap provided with Fig. 3 shows the cup mouth region crimped inwardly to provide for a radially undercut socket chamber adapted to receive and secure the neck of the insulator disc.

Fig. 4 indicates the method by which the cup dome may be drawn to form a stepped crown plate intended for insulator support purposes, while Fig. 5 shows my partially centric partition seat. a

Fig. 6 1s a cross-sectional view of a con- .caVo-convex style ofmetal expansion plug adapted to cooperate with said seat and seal said stepped crown plate with respect to the cup chamber proper to constitute a partitioned link chamber.

Fig. 7 illustrates the manner in which the walls of my link chamber may be cut out into a socket type of insulator cap, with Fig.

8 showing a top view thereof as taken along line 88 of Fig. 7.

Figs. 9 and 10 represent an alternate method for shaping up said link chamber into complementary spaced ear straps for;

the present instance is shown as of-the socket I type adapted to receive the ball head of the support link C1. The mouth or lip edgeof said cap is equipped with an inturned rim B4 serving to snugly mount the neck A1 of the glass, porcelain or similar style of petticoat insulator disc A2. Said disc maybe provided with a centrally disposed socket A3 into which the fixed shank end of the headed link-pin C1 may be firmly cemented or otherwise secured, while the insulator neck Al may likewise be fastened into the radially undercut cap cavity, preferably by a turned conmeans of cement or other suitable filler medium denoted by A4.

Taking up now the making of such a cap structure by my improved method, the first step resides in stamping up by means of any suitable dies, a sheet-metalblank into the simple cup shapedstructure such as is crosssectionally represented by Fig. 2. The end in view is to fashion said blank into a shelllike member providing for a flared tubular skirt portion B1 of substantially straight lined diverging profile; the larger open end portion thereof terminates in -atrimmed or the aforesaid cup skirt somewhat longer than the corresponding finished skirt dimension It of the completely fabricated cap (see Fig. 5). i 3

As a further step-in the making of my inv sulator cap, said rim B l may now be crnnped nwardly' 1n the manner disclosed by Fig. 3 to, form. a radially undercut groove ortion B6 1 in conti uous to the rim re- P y z: a

,gion. The dome element, B5 may now be cessively robbing the metal therefrom or drawnthrough the medium of one or more draw-ring devices, suchpfor instance as the punch I D1 and a. cooperating bottomv die "D2. These are adapted to progressively impart to the center region of said dome, an offset crown plate B3 adaptedffor cap supporting purposes. The semi-spherical crown portion thus formed is preferablyso shaped as to afford a peripheral sidewallelement B3 adjoined bend to the remaining marginal portion of'the annular dome wall B5. As applied to present purposes, the use of said ring die serves to crowd asurplus portion of the original skirt length vH inwardly while only partially drawing down the relatively flat center dome region without exunduly thinning the resulting crown wall formation. a I

. An outstanding advantage gained by first forming up the simple cup-shape and then drawing an integral crown plate thereon, hes in the more un form d1StIlbL1t1OIl- Of metal throughout the finished capproduct. The described forming steps are also. relatively easy tol perform in contrast to similarly shaping up in a single operation, the

cap structure shown Fig. 5; understh'e latter 'CQnditions,,.the metal" would besub- "jected to un'duefstretching strain and the dies far more likely to pierce the dome plate crown, especiallysoi when applied to relativelyheavy sheetnietal blank such as must necessar ly be resorted to infabricating in manner represented in Fig. 7 or 9. I My. invention inpart resides in forming the outer incasing walls ofeither of such sulator caps of the heavy-duty suspension type. If desired, the aforesaid rim crimping operation may be performed subsequent to drawing the crown B3, but by following the stipulated sequence of operations, the shank of the punch D1 may be centered by the inturnedrim in the manner indicated in Fig. 4c.

The crown wall portion of my otherwise completed cap may now be punched or machined out in alternative ways to form upv a compartmentallink chamber B8 adapted for attachment of different styles of supporting links, oneexample of which is depicted'in Figs. 7 and 8. By the use of $1111} able milling tools,- this socket type of'cap support, may be cut to provide for a key hole aperture.B9,[whereuponthe ball head of the link pin, C1 may be pivotally inserted therein andsecured against inadvertent displacement by theconventional cotter pin C2 orthelike. .7

In the alternative cap support means illustrated in Figs. 9 and 10, the Walls of said link chamber B8 may'if preferred, be given amodiiied flattened shape which is cross slotted at B1 0 and theresultingcomplementary ear strapsprovided with extruded alignedapertures B11 adapted to mount the toggle pin B12 therebetween. -Said pin engages a somewhat different type of support link pin C1 in that thisisequipped-with a journaled stub end enlargementof the con" ventional clevis type.

It now remalns to providev fora weatherproof partition between the undercutskirted "socket and the apertured crown portion of my cap. Referring to Fig. 5;, it will be observed that. a seating tool (shown indotted outline) may be entered through the o n mouth of the cap'to countersink a cylin rical seatB13 within the rounded sidewall region lying inwardly of the circumscribing dome portion B5 as shown in dotted outline. Saidv annular seat is preferably sealed by a separately formed expansion plug 'El such as is cross-sectionally detailed in Fig. 6 and in which the edge of the dished disc is initially given a true cylindrical rather than a conical shape; the edge ofthis convexo- 1 15 concave partition disc may be inserted upon said seat in a snugly fitting relationwith the dished crown of the plug faced towardthe. link chamber B8 and away from the inturned cap rim B41. Saidjplugis thereupon partially "flattened in place'by the-use of suitable tools of which one may be entered through either of'the'cited crown apertures to make a weather proof plug joint in the partitioned link chamberintegrally with those of the bell-shaped-skirtwalls o'f my terior surface that can readily be uniformly and flawlessly galvanized for rust prevention purposes. It is expedient to carry he lowermost depending portion of the aperture B9 or the slot B10 closely adjacent to the periphery of the plug E in order to freely drain any rain or accumulated moisture from the link chamber B8 or as a substitute therefor, a drain hole B2 may be resorted to. My method is speciall intended to allow of economically fabricating a cap of this character on a productive scale and to provide for a cap that will be reasonably free from hidden defects or excessive waste when subjected to rigid inspection.

It will be understood that various changes in the structural details or mode of manipulation may be resorted to in carrying out the described method of making insulator caps or the like, and that while it is preferred to follow the operative steps as prescribed, the same results may also be obtained when the order thereof is partially reversed or otherwise modified, all without departing from the spirit and scope of my invention heretofore described and more particularly pointed out in the appended claims.

Claims:

1. The process of stamping from a sheet metal blank, a supportable capv of the under- 7 out socket type adapted to mount on an insulator neck therein, said process including forming said blank into a cup shape comprising a tubular skirt portion of which one end thereof is initially closed by a trans verse dome wall portion, and thereupon, further drawing the central region of said dome into a stepped crown plate and during Which operation the overall length of said skirt is axially contracted by bending inwardly the dome end thereof to contribute metal for forming up the drawn crownportion.

2. The process of stamping from a sheet metal blank, a supportable cap of the undercut socket type adapted to mount an insulator neck therein, said process including forming said blank into a cup shape comprising a tubular skirt portion of which one end is provided with a mouthed rim while the other end thereof is initially closed by a transverse dome wall portion, then crimping inwardly the cup rim region to form an annular radially undercut groove therealong,

s and thereupon by the use of ring-die means introducing the punch member thereof through said grooved cup mouth in a con tered relation to said crimped cup ring for the purpose of drawing out the central dome region into a stepped crown plate adapted for insulator cap support purposes.

3. The process of stamping from a sheet metal blank, a supportable cap of the undercut socket type adapted to mount an insulator neck therein, said process including forming said blank into a cup shape comprising a tubular skirt portion of which one end is provided with a mouthed rim While the other end thereof is initially closed by a transverse dome wall portion, and which dome is subsequently drawn into a stepped crown plate and an interconnecting perimet- 

